Crudup, who recently won an Emmy for drama series for `The Morning Show,` portrayed Dr. Henry Allen as the father to Barry Allen, aka The Flash, in Zach Snyder's 2017 `Justice League` opposite Miller.
The project has gained momentum with Andy Muschietti directing. The `It` helmer revealed in August that he had persuaded Ben Affleck to come on to `The Flash` as Batman in a story in which Miller's Barry Allen would be appearing in parallel dimensions and meeting different versions of DC's heroes. Michael Keaton, who played Batman/Bruce Wayne in Tim Burton's 1989 pic and returned to collaborate with the director in 1992's `Batman Returns,` is also due to appear in `The Flash.`
The script, written by Christina Hodson, will center on Barry Allen going back in time to prevent the murder of his mother, an act that proves to have a profound impact.
Crudup's recent feature credits include Best Picture winner `Spotlight,` `Jackie,` `20th Century Women,` Richard Linklater's `Where'd You Go Bernadette` and the drama `After the Wedding` with Julianne Moore and Michelle Williams. The actor won his Emmy role for playing network executive Cory Ellison opposite Reese Witherspoon and Jennifer Aniston's `Morning Show,` which is prepping for a second season.